In coils for electrical equipment such as inverter-related equipment, for example, high-speed switching devices, inverter motors and transformers, electrical insulated wires (insulated wires), which are enameled wires, are mainly used as magnet wires.
As such insulated wires, multilayer insulated wires having a plurality of covering resin layers formed of resins having different properties are known. For example, Patent Literature 1 proposes composite enameled wires having a polyester resin coating layer and a low imide-modified polyester resin coating layer.